The present invention is directed to anticonvulsant derivatives useful in the treatment of depression, specifically unipolar depression, treatment-refractory depression, resistant depression, anxious depression and dysthymia. The present invention is further directed to the treatment of depression comprising administration of one or more anticonvulsant derivatives in combination with one or more compounds selected from mono-amine oxidase inhibitors, tricyclics, serotonin reuptake inhibitors, serotonin noradrenergic reuptake inhibitors, noradrenergic and specific serotonergic agents, noradrenaline reuptake inhibitors, natural products, dietary supplements, neuropeptides, compounds targeting neuropeptide receptors or hormones.
Compounds of Formula I: 
are structurally novel antiepileptic compounds that are highly effective anticonvulsants in animal tests (MARYANOFF, B. E, NORTEY, S. O., GARDOCKI, J. F., SHANK, R. P. AND DODGSON, S. P. J. Med. Chem. 1987, 30, 880-887; MARYANOFF, B. E., COSTANZO, M. J., SHANK, R. P., SCHUPSKY, J. J., ORTEGON, M. E., AND VAUGHT J. L. Bioorg. Med. Chem. Lett. 1993, 3, 2653-2656; SHANK, R. P., GARDOCKI, J. F., VAUGHT, J. L., DAVIS, C. B., SCHUPSKY, J. J., RAFFA, R. B., DODGSON, S. J., NORTEY, S. O., MARYANOFF, B. E. Epilepsia 1994, 35, 450-460; MARYANOFF B E, COSTANZO M J, NORTEY S O, GRECO M N, SHANK R P, SCHUPSKY J J, ORTEGON M P, VAUGHT J L. J. Med. Chem. 1998, 41, 1315-1343). These compounds are covered by three U.S. Pat. Nos.: 4,513,006, 5,242,942, and 5,384,327. One of these compounds 2,3:4,5-bis-O-(1-methylethylidene)-xcex2-D-fructopyranose sulfamate, known as topiramate, has been demonstrated in clinical trials of human epilepsy to be effective as adjunctive therapy or as monotherapy in treating simple and complex partial seizures and secondarily generalized seizures (E. FAUGHT, B. J. WILDER, R. E. RAMSEY, R. A. REIFE, L D. KRAMER, G. W. PLEDGER, R. M. KARIM et. al., Epilepsia 1995, 36 (S4), 33; S. K. SACHDEO, R. C. SACHDEO, R. A. REIFE, P. LIM and G. PLEDGER, Epilepsia 1995, 36 (S4), 33; T. A. GLAUSER, Epilepsia 1999, 40 (S5), S71-80; R. C. SACHDEO, Clin. Pharmacokinet. 1998, 34, 335-346), and is currently marketed for the treatment of seizures in patients with simple and complex partial epilepsy and seizures in patients with primary or secondary generalized seizures in the United States, Europe and most other markets throughout the world.
Compounds of Formula I were initially found to possess anticonvulsant activity in the traditional maximal electroshock seizure (MES) test in mice (SHANK, R. P., GARDOCKI, J. F., VAUGHT, J. L., DAVIS, C. B., SCHUPSKY, J. J., RAFFA, R. B., DODGSON, S. J., NORTEY, S. O., and MARYANOFF, B. E., Epilepsia 1994, 35, 450-460). Subsequent studies revealed that Compounds of Formula I were also highly effective in the MES test in rats. Topiramate was also found to effectively block seizures in several rodent models of epilepsy (J. NAKAMURA, S. TAMURA, T. KANDA, A. ISHII, K. ISHIHARA, T. SERIKAWA, J. YAMADA, and M. SASA, Eur. J. Pharmacol. 1994, 254, 83-89), and in an animal model of kindled epilepsy (A. WAUQUIER and S. ZHOU, Epilepsy Res. 1996, 24, 73-77).
Compounds of formula I have further been found to be effective in the treatment of manic depressive bipolar disorder (Shank, U.S. Pat. No. 5,753,693).
Tollefson et al in WIPO Publication WO99/62522 disclose a method for the treatment of bipolar disease, bipolar depression or unipolar depression comprising administration of an atypical antipsychotic in combination with a compound selected from the group consisting of serotonin reuptake inhibitors, anticonvulsants and lithium.
Unipolar depression is defined as depressed mood on a daily basis for a minimum duration of two weeks. An episode may be characterized by sadness, indifference or apathy, or irritability and is usually associated with a change in a number of neurovegetative functions, including sleep patterns, appetite and body weight, motor agitation or retardation, fatigue, impairment in concentration and decision making, feelings of shame or guilt, and thoughts of death or dying (Harrison""s Principles of Internal Medicine, 2000). The criteria for a major depressive episode includes five or more symptoms present during the same 2-week period, where this represents a change from previous functioning; and where at least one of the symptoms is either depressed mood or loss of interest or pleasure. Symptoms of a depressive episode include depressed mood; markedly diminished interest or pleasure in all, or almost all, activities most of the day; weight loss when not dieting or weight gain, or decrease or increase in appetite nearly every day; insomnia or hypersomnia nearly every day; psychomotor agitation or retardation nearly every day; fatigue or loss of energy nearly every day; feelings of worthlessness or excessive or inappropriate guilt nearly every day; diminished ability to think or concentrate, or indecisiveness, nearly every day; recurrent thoughts of death, recurrent suicidal ideation without a specific plan, or a suicide attempt or a specific plan for committing suicide. Further, the symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning. (Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, American Psychiatric Association, 1994).
Current treatment options for unipolar depression include monotherapy or combination therapy with various classes of drugs including mono-amine oxidase inhibitors, tricyclics, serotonin reuptake inhibitors, serotonin noradrenergic reuptake inhibitors, noradrenergic and specific serotonergic agents, noradrenaline reuptake inhibitor, xe2x80x9cnatural productsxe2x80x9d (such as Kava-Kava, St. John""s Wort), dietary supplement (such as s-adenosylmethionine) and others. More specifically, drugs used in the treatment of depression include, but are not limited to imipramine, amitriptyline, desipramine, nortriptyline, doxepin, protriptyline, trimipramine, maprotiline, amoxapine, trazodone, bupropion, chlomipramine, fluoxetine, citalopram, sertraline, paroxetine, fluvoxamine, nefazadone, venlafaxine, reboxetine, mirtazapine, phenelzine, tranylcypromine, and/or moclobemide (eg, J. M. KENT, Lancet 2000, 355, 911-918; J. W. WILLIAMS JR, C. D. MULROW, E. CHIQUETTE, P. H. NOEL, C. AGUILAR, and J. CORNELL, Ann. Intern. Med. 2000, 132, 743-756; P. J. AMBROSINI, Psychiatr. Serv. 2000, 51, 627-633). Several of these agents including, but not limited to, serotonin reuptake inhibitors are also used when depression and anxiety co-exist, such as in anxious depression (R. B. LYDIARD and O. BRAWMAN-MINTZER, J. Clin. Psychiatry 1998, 59, Suppl. 18, 10-17; F. ROUILLON, Eur. Neuropsychopharmacol. 1999, 9 Suppl. 3, S87-S92).
In the clinic, 40-50% of depressed patients who are initially prescribed antidepressant therapy do not experience a timely remission of depression symptoms. This group typifies treatment-refractory depression, that is, a failure to demonstrate an xe2x80x9cadequatexe2x80x9d response to an xe2x80x9cadequatexe2x80x9d treatment trial (that is, sufficient intensity of treatment for sufficient duration) (R. M. BERMAN, M. NARASIMHAN, and D. S. CHARNEY, Depress. Anxiety 1997, 5, 154-164). Moreover, about 20-30% of depressed patients remain partially or totally resistant to pharmacological treatment including combination treatments (J. ANANTH, Psychother. Psychosom. 1998, 67, 61-70; R. J. CADIEUX, Am. Fam. Physician 1998, 58, 2059-2062). Increasingly, treatment of resistant depression includes augmentation strategies including treatment with pharmacological agents such as, lithium, carbamazepine, and triiodothyronine, and the like (M. HATZINGER and E. HOLSBOER-TRACHSLER, Wien. Med. Wochenschr. 1999, 149, 511-514; C. B. NEMEROFF, Depress. Anxiety 1996-1997, 4, 169-181; T. A. KETTER, R. M. POST, P. I. PAREKH and K. WORTHINGTON, J. Clin. Psychiatry 1995, 56, 471-475; R. T. JOFFE, W. SINGER, A. J. LEVITT, C. MACDONALD, Arch. Gen. Psychiatry 1993, 50, 397-393).
Dysthymia is defined as a mood disorder characterized by chronic depressed mood for a period of at least 2 years. Dysthymia can have a persistent or intermittent course and the depressed mood occurs for most of the day, for more days than not, and for at least 2 years. (Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, American Psychiatric Association, 1994).
Bipolar disorder, on the other hand, is characterized by unpredictable swings in mood between mania and depression (bipolar I disorder) or between hypomania and depression (bipolar II disorder) (Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, American Psychiatric Association, 1994). Antidepressant use in bipolar disorder is generally, intentionally restricted to avoid the risk of mania and the risk of rapid cycling induced by antidepressants in bipolar disorder (H. J. MOLLER and H. GRUNZE, Eur. Arch. Psychiatry Clin. Neurosci. 2000, 250, 57-68; J. R. CALABRESE, D. J. RAPPORT, S. E. KIMMEL, and M. D. SHELTON, Eur. Neuropsychopharmacol. 1999, 9, S109-S112). Moreover, none of the mood stabilizers used in bipolar disorder have proven antidepressive efficacy (H. J. MOLLER and H. GRUNZE, Eur. Arch. Psychiatry Clin. Neurosci. 2000, 250, 57-68).
Accordingly, it has been found that compounds of the following formula (I): 
wherein X is O or CH2, and R1, R2, R3, R4 and R5 are as defined hereinafter are useful in treating depression, specifically unipolar depression, treatment-refractory depression, resistant depression, anxious depression and dysthymia.
In an embodiment of the present invention, the depression is selected from the group consisting of unipolar depression, treatment refractory depression, resistant depression and anxious depression.
In an embodiment of the present invention is a method for the treatment of depression comprising administering to a subject in need thereof a combination of one or more compounds of formula I with one or more compounds selected from the group consisting of mono-amine oxidase inhibitors such as phenelzine, tranylcypromine, moclobemide, and the like; tricyclics such as imipramine, amitriptyline, desipramine, nortriptyline, doxepin, protriptyline, trimipramine, chlomipramine, amoxapine, and the like; tetracyclics such as maprotiline, and the like; non-cyclics such as nomifensine, and the like; triazolopyridines such as trazodone, and the like; serotonin reuptake inhibitors such as fluoxetine, sertraline, paroxetine, citalopram, fluvoxamine, and the like; serotonin receptor antagonists such as nefazadone, and the like; serotonin noradrenergic reuptake inhibitors such as venlafaxine, milnacipran and the like; noradrenergic and specific serotonergic agents such as mirtazapine, and the like; noradrenaline reuptake inhibitors such as reboxetine, and the like; atypical antidepressants such as bupropion, and the like; natural products such as Kava-Kava, St. John""s Wort, and the like; dietary supplements such as s-adenosylmethionine., and the like; and neuropeptides such as thyrotropin-releasing hormone and the like, and the like; compounds targeting neuropeptide receptors such as neurokinin receptor antagonists and the like; and hormones such as triiodothyronine, and the like.
In an embodiment of the present invention is a method for the treatment of depression comprising administering to a subject in need thereof a combination of one or more compounds of formula I with one or more compounds selected from the group consisting of mono-amine oxidase inhibitors; tricyclics; tetracyclics; non-cyclics; triazolopyridines; serotonin reuptake inhibitors; serotonin receptor antagonists; serotonin noradrenergic reuptake inhibitors; serotonin noradrenergic reuptake inhibitors; noradrenergic and specific serotonergic agents; noradrenaline reuptake inhibitors; atypical antidepressants; natural products; dietary supplements; neuropeptides; compounds targeting neuropeptide receptors; and hormones.
Preferably, one or more compounds of formula I are administered in combination with one or more compounds selected from the group consisting of mono-amine oxidase inhibitors, tricyclics, serotonin reuptake inhibitors, serotonin noradrenergic reuptake inhibitors; noradrenergic and specific serotonergic agents and atypical antidepressants.
More preferably, one or more compounds of formula I are administered in combination with one or more compounds selected from the group consisting of mono-amino oxidase inhibitors, tricyclics and serotonin reuptake inhibitors.
Most preferably, one or more compounds of formula I are administered in combination with one or more compounds selected from the group consisting of serotonin reuptake inhibitors.
In an embodiment of the present invention is a method for the treatment of depression comprising administering to a subject in need thereof a combination of one or more compounds of formula I with one or more compounds selected from the group consisting of phenelzine, tranylcypromine, moclobemide, imipramine, amitriptyline, desipramine, nortriptyline, doxepin, protriptyline, trimipramine, chlomipramine, amoxapine, fluoxetine, sertraline, paroxetine, citalopram, fluvoxamine, venlafaxine, milnacipran, mirtazapine, bupropion, thyrotropin-releasing hormone and triiodothyronine.
Preferably, one or more compounds of formula I are administered in combination with one or more compounds selected from the group consisting of phenelzine, tranylcypromine, moclobemide, imipramine, amitriptyline, desipramine, nortriptyline, doxepin, protriptyline, trimipramine, chlomipramine, amoxapine, fluoxetine, sertraline, paroxetine, citalopram, fluvoxamine, venlafaxine, milnacipran, mirtazapine and bupropion.
More preferably, one or more compounds of formula I are administered in combination with one or more compounds selected from the group consisting of phenelzine, tranylcypromine, moclobemide, imipramine, amitriptyline, desipramine, nortiptyline, doxepin, protriptyline, trimipramine, chlomipramine, amoxapine, fluoxetine, sertraline, paroxetine, citalopram and fluvoxamine.
Most preferably, one or more compounds of formula I are administered in combination with one or more compounds selected from the group consisting of fluoxetine, sertraline, paroxetine, citalopram and fluvoxamine.
In an embodiment of the present invention, is a method for the treatment of depression comprising administering to a subject in need thereof a combination of one or more compounds of formula I with one or more compounds selected from the group consisting of neuropeptides such as thyrotropin-releasing hormone and the like; compounds targeting neuropeptide receptors such as neurokinin receptors antagonists and the like; and hormones such as triiodothyronine and the like.
As used herein, the term xe2x80x9cdepressionxe2x80x9d shall be defined as unipolar depression, treatment-refractory depression, resistant depression, anxious depression and dysthymia.
The sulfamates of the invention are of the following formula (I): 
wherein
X is CH2 or oxygen;
R1 is hydrogen or alkyl; and
R2, R3, R4 and R5 are independently hydrogen or lower alkyl and, when X is CH2, R4 and R5 may be alkene groups joined to form a benzene ring and, when X is oxygen, R2 and R3 and/or R4 and R5 together may be a methylenedioxy group of the following formula (II): 
wherein
R6 and R7 are the same or different and are hydrogen, lower alkyl or are alkyl and are joined to form a cyclopentyl or cyclohexyl ring.
R1 in particular is hydrogen or alkyl of about 1 to 4 carbons, such as methyl, ethyl and iso-propyl. Alkyl throughout this specification includes straight and branched chain alkyl. Alkyl groups for R2, R3, R4, R5, R6 and R7 are of about 1 to 3 carbons and include methyl, ethyl, iso-propyl and n-propyl. When X is CH2, R4 and R5 may combine to form a benzene ring fused to the 6-membered X-containing ring, i.e., R4 and R5 are defined by the alkatrienyl group xe2x95x90Cxe2x80x94CHxe2x95x90CHxe2x80x94CHxe2x95x90.
A particular group of compounds of formula (I) is that wherein X is oxygen and both R2 and R3 and R4 and R5 together are methylenedioxy groups of the formula (II), wherein R6 and R7 are both hydrogen both alkyl or combine to form a spiro cyclopentyl or cyclohexyl ring, in particular where R6 and R7 are both alkyl such as methyl. A second group of compounds is that wherein X is CH2 and R4 and R5 are joined to form a benzene ring. A third group of compounds of formula (I) is that wherein both R2 and R3 are hydrogen.
The compounds of formula (I) may be synthesized by the following methods:
(a) Reaction of an alcohol of the formula RCH2OH with a chlorosulfamate of the formula CISO2NH2 or CISO2NHR1 in the presence of a base such as potassium t-butoxide or sodium hydride at a temperature of about xe2x88x9220xc2x0 to 25xc2x0 C. and in a solvent such as toluene, THF, or dimethylformamide wherein R is a moiety of the following formula (III): 
(b) Reaction of an alcohol of the formula RCH2OH with sulfurylchloride of the formula SO2Cl2 in the presence of a base such as triethylamine or pyridine at a temperature of about xe2x88x9240xc2x0 to 25xc2x0 C. in a solvent such as diethyl ether or methylene chloride to produce a chlorosulfate of the formula RCH2OSO2Cl.
The chlorosulfate of the formula RCH2OSO2Cl may then be reacted with an amine of the formula R1NH2 at a temperature of abut 40xc2x0 to 25xc2x0 C. in a solvent such as methylene chloride or acetonitrile to produce a compound of formula (I). The reaction conditions for (b) are also described by T. Tsuchiya et al. in Tetrahedron Lett., 1978, 3365.
(c) Reaction of the chlorosulfate RCH2OSO2Cl with a metal azide such as sodium azide in a solvent such as methylene chloride or acetonitrile yields an azidosulfate of the formula RCH2OSO2N3 as described by M. Hedayatullah in Tetrahedron Lett. 1975, 2455. The azidosulfate is then reduced to a compound of formula (I) wherein R1 is hydrogen by catalytic hydrogenation, e.g. with a noble metal and H2 or by heating with copper metal in a solvent such as methanol.
The starting materials of the formula RCH2OH may be obtained commercially or as known in the art. For example, starting materials of the formula RCH2OH wherein both R2 and R3 and R4 and R5 are identical and are of the formula (II) may be obtained by the method of R. F. Brady in Carbohydr. Res. 1970, 14, 35 or by reaction of the trimethylsilyl enol ether of a R6COR7 ketone or aldehyde with fructose at a temperature of about 25xc2x0 C., in a solvent such a halocarbon, e.g. methylene chloride in the presence of a protic acid such as hydrochloric acid or a Lewis Acid such as zinc chloride. The trimethylsilyl enol ether reaction is described by G. L. Larson et al. in J. Org. Chem. 1973, 38, 3935.
Further, carboxylic acids and aldehydes of the formulae RCOOH and RCHO may be reduced to compounds of the formula RCH2OH by standard reduction techniques, e.g. reaction with lithium aluminum hydride, sodium borohydride or borane-THF complex in an inert solvent such a diglyme, THF or toluene at a temperature of about 0xc2x0 to 100xc2x0 C., e.g. as described by H. O. House in xe2x80x9cModern Synthetic Reactionsxe2x80x9d, 2nd Ed., pages 45 to 144 (1972).
The compounds of formula I: may also be made by the process disclosed U.S. Pat. Nos.: 4,513,006, 5,242,942, and 5,384,327, which are incorporated by reference herein.
The compounds of formula I include the various individual isomers as well as the racemates thereof, e.g., the various alpha and beta attachments, i.e., below and above the plane of the drawing, of R2, R3, R4 and R5 on the 6-membered ring. Preferably, the oxygen of the methylenedioxy group (II) are attached on the same side of the 6-membered ring.
The ability of the compounds of formula I to treat depression is based on the results of clinical case studies in which topiramate was added to existing pharmacotherapy in two patients with diagnosed depression.